Biochemical analyses of Drosophila single-gene mutants, isolated for their effects on associative learning and memory, have implicated the monoamine-stimulated adenylate cyclase pathway. Behavioral analyses of other mutations isolated for their effects on specific biochemical or physiological systems will broaden our understanding of the biological mechanisms underlying associative learning and memory. Of particular interest are mutations affecting biogenic amine metabolism or neuronal ion channels, since they provide empirical tests of a current model of associative learning. Long-term memory formation will be studied in memory consolidation experiments and by assessing the stability of memory through metamorphosis in normal and mutant flies. A study of memory through metamorphosis in mutants with degenerated brain structures may identify specific anatomical sites involved with long-term memory storage or retrievel. Anatomical sites involved with associative learning also will be identified by generating flies mosaic for normal and mutant tissue. Behavioral analyses of learning or memory in these mosaics may reveal the existence of "learning foci" in the brain.